Synthesis Of Carbon Nanocoils Research Articles

Highly efficient synthesis of carbon nanocoils on alumina spheres

Carbon nanocoils (CNCs) and carbon nanotubes (CNTs) can be selectively synthesized on the surfaces of alumina spheres using an Fe2(SO4)3/SnCl2 catalyst with different molar ratios of Fe to Sn by a thermal chemical vapor deposition method.

Synthesis of carbon nanocoils on substrates made of plant fibers

Carbon nanocoils (CNCs) with different shapes and coil diameters have been synthesized on three kinds of substrates made of plant fibers, i.e. tissue, cotton cloth and bamboo fiber cloth, using Fe2 (SO4)3/SnCl2 catalyst by a thermal chemical vapor deposition method. The average coil diameters of the CNCs on the tissue, cotton cloth and bamboo fiber cloth substrates are 560, 183, and 510nm, respectively. It is found that the organization difference in the plant fiber substrates results in the difference in the aggregation states of catalyst particles on the fiber surfaces, which has a crucial effect on the morphology and production of the grown CNCs. The tight organization of the carbon fibers in the tissue and cotton cloth substrates can promote the catalyst aggregations to fabricate high yield CNCs. For the bamboo fiber cloth substrate, a relatively small number of catalyst particles are deposited on the surface and tend to be isolated, leading to the growth of a certain amount of the carbon nanofibers and carbon nanotubes. In addition, the catalyst adsorption ability of the bamboo fiber can be improved by coating calcium chloride particles to achieve high production of the regular CNCs.

Synthesis of Nitrogen-Doped Carbon Nanocoils with Adjustable Morphology Using Ni—Fe Layered Double Hydroxides as Catalyst Precursors

Nitrogen-doped carbon nanocoils (CNCs) with adjusted morphologies were synthesized in a one-step catalytic chemical vapour deposition (CVD) process using acetonitrile as the carbon and nitrogen source. The nickel iron oxide/nickel oxide nanocomposites, which were derived from nickel–iron layered double hydroxide (LDH) precursors, were employed as catalysts for the synthesis of CNCs. In this method, precursor-to-catalyst transformation, catalyst activation, formation of CNCs, and nitrogen doping were all performed in situ in a single process. The morphology (coil diameter, coil pitch, and fibre diameter) and nitrogen content of the synthesized CNCs was individually adjusted by modulation of the catalyst composition and CVD reaction temperature, respectively. The adjustable ranges of the coil diameter, coil pitch, fibre diameter, and nitrogen content were confirmed to be approximately 500±100 nm, 600±100 nm, 100±20 nm, and 1.1±0.3 atom%, respectively.

Study of the Synthesis Conditions of Carbon Nanocoils for Energetic Applications

The synthesis of carbon nanocoils (CNCs) by the catalytic graphitization of composites has been studied. Resorcinol-formaldehyde gel was used as the carbon precursor; a mixture of cobalt and nickel salts was used as the graphitization catalysts in the synthesis; and silica sol was added to the reaction mixture to obtain carbon materials with high specific surface area and to achieve a good dispersion of the transition-metal nanoparticles. Different molar ratios of the reagents were used with the purpose of obtaining carbon materials with different structural and textural properties, seeking a compromise between the graphitization degree and surface area. X-ray diffraction (XRD), Raman spectrometry, transmission electron microscopy (TEM), temperature-programmed oxidation (TPO), N 2 physisorption, and temperature-programmed desorption (TPD) were used to characterize the morphology, textural properties, and surface chemistry of such materials. Results showed that obtained CNCs had good crystallinity and well-defined porosity, which depended upon the preparation conditions.

Growth of Carbon Nanocoils Using Chemical Vapor Deposition

We present the synthesis of carbon nanocoils using the chemical vapor deposition technique with metal catalysts on silicon substrates. The optimum synthesis conditions and coil geometry are summarized. The coils have distribution of the outside diameter of 300 nm to 1200 nm, wire diameter of 150 nm to 400 nm and the pitch of the coil of 150 nm to 1200 nm. Applications of the developed carbon nanocoils can be electro-mechanical sensing and the electro-magnetic insulation.

カーボンナノコイルの低温合成

Synthesis of carbon nanocoils was carried out by the simple apparatus based on hot-filament CVD at catalyst temperatures below 450ºC. Copper was vacuum evaporated onto the nickel particles formed by scratching the poly-crystal nickel plate with sandpaper. These particles were used for the catalysts for synthesis of nanocoils. Heating was not performed at all for forming these particles. Ethanol as a carbon source was introduced into the chamber with argon gas. Synthesis was performed at atmospheric pressure. Carbon nanocoils could be synthesized at temperatures above 400ºC. The yield of nanocoils in total carbon fibers is about 80% at 400ºC. The diameter of these products decreases with the decrease of diameter of catalyst particles.

Synthesis of carbon nanocoils on surface morphology changed silicon substrates

By the controlled corrosion of HF, silicon substrates appeared to be in a state of concavo-convex morphology. Carbon nanocoils were synthesized on these silicon substrates by the pyrolysis of acetylene with catalytic thermal chemical vapor deposition (CVD). Scanning electron microscopy and transmission electron microscopy were carried out to observe the regular morphology of carbon nanocoils, while Raman spectra was used to characterize the graphitization degree. The growing process of the nanocoils was regarded as the anisotropic activity of catalyst particles resulting from the different thicknesses of FeO layer.

Use of Catalysts in the Synthesis of Carbon Nanocoils

Because of their unique 3 D structure, carbon nanocoils have potential applications to electromagnetic components, such as nanosolenoids and electromagnetic wave absorbers, and mechanical components, such as resonating elements and nanosprings or as a novel reinforcement in high-strain composites. The other potential application is to field emission devices. The stable synthesis of these nanocoils has been made possible by developing the catalysts containing Fe, In and Sn. Recently, the coil diameter has also been able to be controlled by the adjustment of the synthesis condition and the modification of the catalyst. The use of thin nanocoils, for example, enables us to develop the spatially-uniform field-emission-devices with the turn-on voltage as low as 30 V.

Synthesis of carbon nanocoils by microwave CVD

The carbon nanocoil is an interesting kind of nanomaterial, which is expected tohave various novel applications in microelectronics, microelectromechanicalsystems (MEMS) and bioMEMS due to its nanosize coil morphology. Carbonnanocoils were synthesized by catalytic pyrolysis of acetylene over 2.2–3.0 µm Niparticles at 600°C in a microwave chemical vapour deposition (CVD) system.Microwave CVD derived nanocoils are rather uniform with an average coildiameter of 110–170 nm, fibre diameter of 80–120 nm and pitch of around 130–200nm. The effects of reaction temperature, the size of Ni catalyst and the flow rateof acetylene were examined. Additionally, the growth mechanism of carbonnanocoils was studied. It was found that two individual carbon nanocoils extrudefrom the same Ni particle in the same direction as straight fibres at thebeginning and then bend to grow into nanocoils in opposite directions.